What you put into your digester, determines what comes out. In your process, you have to ensure that the feedstock is producing sufficient yield to make it viable.
Feedstock in the process can be anything from household food waste, wastewater, sludge, or even energy crops that can be specifically grown to get the best yield from your digesters.
Often on farms, waste from the animals is used for the process, however, the waste from animals produces far less biogas per ton than particular energy crops. This is contrasted by the fact that the cost, security, and constant production of the waste allows the process to be stable. Whereas, energy crops have to be grown and then harvested, along with many other variables that could affect the process.
For reference, cattle slurry can produce up to 16m3/t of biogas yield. Whereas some energy crops can produce in excess of 600m3/t due to their properties.
Treating the feedstock is imperative in the AD process. You don’t want to have large particles of substrate in your digesters, making the breakdown a prolonged and difficult process.
The best way of ensuring that your digesters are being fed with the correct size substrate is maceration of the feedstock. The homogenisation ensures that every particle is broken down to allow the most effective biogas yield.
Also, by macerating the feedstock, it reduces the strain on the pumping aspects of your process. This means that material can be transferred from a storage vessel, into the digesters efficiently. The same can be said for transportation after the reaction has taken place.
